In conventional blower units, a fan generating air flow may be accommodated in a scroll casing and two ducts may be provided around the scroll casing. The scroll casing may rotate around an axis thereof and stop at two positions. In one position, a discharge port of the scroll casing may be connected to an inlet of one duct. In the other position, a discharge port of the scroll casing may be connected to an inlet of the other duct. In conventional blower units, it may not be clear how to stop the scroll casing. Further, it may be difficult to stop the scroll casing at a desired position.